A bunion is a bony bump that forms on the joint at the base of the big toe. It happens when some of the bones in the front part of the foot move out of their regular position. This causes the big toe to get pulled toward the smaller toes. It also forces the joint at the base of your big toe to stick out. The skin over the bunion might change in color and feel sore.
Wearing tight, narrow shoes might cause bunions or make them worse. Bunions also can form due to the shape of the foot, a foot defect or a condition such as arthritis.
Smaller bunions, called bunionettes, can form on the joint of the little toe.

With a bunion, the big toe shifts toward the smaller toes, crowding them. This also forces the joint at the base of the big toe to stick out.

A smaller bunion, called a bunionette, can form on the joint of the little toe.
The symptoms of a bunion include:
Bunions often don't need medical treatment. But some symptoms should be checked by a member of your health care team. Or you could see a doctor who treats foot conditions, called a podiatrist, or an orthopedic foot specialist. Get a checkup if you have:
Many theories exist about how bunions form. But the exact cause isn't clear. Factors likely include:
Experts disagree on the role that shoes play. Some say that tight, high-heeled or narrow shoes cause bunions. Others say that footwear simply contributes to bunions forming.
Bunions might be linked with some types of arthritis. The link is especially strong with types of arthritis that involve painful swelling due to a problem with the immune system. These conditions include rheumatoid arthritis.
These factors might raise the risk of bunions:
Bunions can lead to health problems that include:
To help prevent bunions, choose shoes carefully. They should be supportive and have a wide toe box — no pointy toes. There also should be space between the tip of your longest toe and the end of the shoe.
Your shoes should match the shape of your feet without squeezing or pressing any part of your foot.